<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        div{
            width: 200px;
            height: 200px;
            margin: 100px auto;
            padding: 50px;
            border: 5px dashed red;
            background-color: yellow;
            /* 默认不填充border */
            background-clip: padding-box ;
            /* 默认背景填充区域 */
            /*background-clip: border-box ;*/
            /* 可以修改我的背景区域 */
            /*background-clip: content-box ;*/


        }
    </style>
</head>
<body>
    <div></div>
</body>
</html>